Currently, a boron neutron capture therapy (BNCT) has attracted attention as a technique that is capable of selectively killing and treating cancer cells. In the BNCT, since it is required to utilize thermal neutrons and epithermal neutrons, there are many restrictions, for example, patients need to visit a reactor which can generate and utilize neutrons. Thus, a compact neutron generator capable of generating neutrons even in hospitals is desired. In the neutron generator, proton and deuteron accelerated in an accelerator are made to collide with target of beryllium or lithium.
As a conventional accelerator, an accelerator described in Non Patent Literature 1 has been known. The accelerator has a configuration in which an ECR (electron cyclotron resonance) type ion source, a radio frequency quadrupole linear accelerator (RFQ linac), and a drift tube type linear accelerator (DTL) are continuously provided. In the accelerator, the deuteron ions are accelerated up to 5 MeV by the RFQ linac and are accelerated up to 40 MeV by the DTL. Liquid lithium which flows over a curved back wall is irradiated with beam of the accelerated deuteron ions to generate neutrons behind the liquid lithium.